:root{/*根元素*/
    --line-border-fill:#3498db;
    --line-border-empty:#e0e0e0;
}

*{
    box-sizing: border-box;
}

body{
    background-color: #f6f7fb;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    overflow :hidden;
    margin:0;
}

.container{
    text-align: center;
}

.progress_container{
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: relative;
    margin :30px;
    max-width: 100%;
    width: 350px;
}

.progress_container::before{/*伪元素*/
    content: '';
    background-color: var(--line-border-empty);
    position: absolute;
    top: 50%;
    left: 0;
    transform: translateY(-50%);
    height: 4px;
    width: 100%;
    z-index: -1;
}

.progress{
    background-color: var(--line-border-fill);
    position: absolute;
    top: 50%;
    left: 0;
    transform: translateY(-50%);
    height: 4px;
    width: 0%;
    z-index: -1;
}

.circle{
    background-color: #fff;
    color: #999;
    border-radius: 50%;
    height: 30px;
    width: 30px;
    display: flex;
    justify-content: center;
    align-items: center;
    border: 3px solid var(--line-border-empty);
    transition: 0.4s ease;
}

.circle.active{
    border-color: var(--line-border-fill);
}

.btn:active{/*按钮加颜色*/
    transform: scale(0.98);
}

.btn:focus{
    outline: none;
}

.btn:disabled{
    background-color: var(--line-border-empty);
    cursor: not-allowed;
}